This invention relates, in general, to semiconductor devices, and more particularly, to a semiconductor device used for detecting hydrogen.
It would be desirable to be able to detect the amount of hydrogen present in an ambient for safety reasons, among others. It would also be desirable to be able to detect the amount of hydrogen that is present in a semiconductor device. Hydrogen is introduced into the semiconductor device during and subsequent to processing. It is known that hydrogen affects the avalanche voltage of a P-N junction, however, the mechanism has not been well understood.
In the past, the presence of hydrogen has been detected by porous membrane hydrogen detectors. Porous membrane hydrogen detectors allow only hydrogen to go through them, thus the amount of hydrogen can be measured. Palladium membranes have been placed on top of MOS devices in the past. This method, however, is undesirable because it is not reproducible and stable. In addition, porous membrane hydrogen detectors measure just the total amount of hydrogen in the ambient. However, once the hydrogen has diffused into the semiconductor device, a certain amount of hydrogen may be trapped beneath certain layers, such as nitride layers of the semiconductor device. Some of the hydrogen will also be bound by a nitride layer. Thus, it would be desirable to be able to detect the amount of unbound hydrogen in the semiconductor device, because that is the hydrogen that causes a change in the avalanche voltage of the device. Furthermore, it would be desirable to be able to clear or reset the device of any hydrogen or other interfering atoms or ions that are introduced into the device during manufacturing or anytime thereafter. Once cleared or reset, the device can be used to detect the amount of hydrogen in air or other gaseous mixtures.
Another way to measure the total content of hydrogen present in a semiconductor device is by the use of Secondary Ion Mass Spectroscopy (SIMS). Although this technique is accurate, it is expensive and destructive, and typically the semiconductor device must be sent out to a lab to have the analysis done. It would be desirable to be able to detect the presence of hydrogen quickly and inexpensively.
Accordingly, it is an object of the present invention to provide a method and device for detecting hydrogen.
Another object of the present invention is to provide a hydrogen detector having electrical reset capability.
An additional object of the present invention is to provide a hydrogen detector that detects unbound hydrogen that causes degradation in device characteristics.
A further object of the present invention is to provide a hydrogen detector that can be cleared of interfering elements before operation.
Yet another object of the present invention is to provide a hydrogen detector that can detect the amount of hydrogen in air or other gaseous mixtures.